The stock dropped as much as 6.7 percent after company officials said in a conference call with investors that they were not yet planning a late-stage trial that would combine two of its drugs as a treatment for lung cancer.

Instead, Bristol-Myers said it would continue a midstage study of the drugs — an experimental medicine called nivolumab and an approved melanoma treatment called Yervoy — before moving them into a larger Phase III lung cancer trial. Both drugs enhance the immune system’s ability to fight cancer.

“Many investors expected Bristol-Myers to rapidly advance the Nivo-Yervoy combo to Phase III, with the plans for such a move perhaps being announced as early as today,” said Alex Arfaei, an analyst at BMO, in a research note. The company’s slower timetable might be interpreted as a sign of caution or suggest a lack of “synergy” between the two drugs when treating lung cancer, he said.

Shares of Bristol closed down 5.6 percent at $50.94.

The company reported quarterly earnings of $726 million, or 44 cents a share. That compares with $925 million, or 56 cents a share, in the period a year earlier, when it took a big write-off for a failed hepatitis C drug. Excluding special items, the profit was 51 cents a share, above the analysts’ average estimate of 43 cents, according to Thomson Reuters I/B/E/S.